Lesser cornstalk borer, Elasmopalpus lignosellus Zeller (Lepidoptera: Pyralidae), is an important sugarcane pest in southern Florida. Development of immature stages (eggs, larvae, prepupae, and pupae) of lesser cornstalk borer was observed on sugarcane at constant temperatures (13, 15, 18, 21, 24, 27, 30, 33, and 36 degrees C), 65-70% RH, and a photoperiod of 14:10 (L:D) h. Total development (from egg deposition to adult emergence) ranged from 22.8 +/- 0.3 d at 33 degrees C to 120.7 +/- 2.8 d at 13 degrees C. Lesser cornstalk borer required 543.48 DD to complete development. Developmental time decreased with increase in temperature from 13 to 33 degrees C and increased markedly at 36 degrees C in all immature stages. One linear and six nonlinear models used to model insect development (Briere-1, Briere-2, Logan-6, Lactin, Taylor, and polynomial models) were tested to describe the relationship between temperature and developmental rate (d(-1)). Criteria used to select the best model were the greatest r (2), lowest residual sum of squares (RSS), and Akaike information criterion values. The Briere-1 model fit the data best and provided the best estimates of developmental temperature thresholds for all immature stages on sugarcane. The estimated lower and upper developmental thresholds for total development were 9.3 +/- 1.8 and 37.9 +/- 0.7 degrees C, respectively. The optimal temperature estimated for the total development was 31.39 +/- 0.9 degrees C. Based on these results, we can forecast the different stages of lesser cornstalk borer at different times in sugarcane. This will enable us to choose the best time to control this pest with greater precision.

Summary• Brake fern, Pteris vittata , not only tolerates arsenic but also hyperaccumulates it in the frond. The hypothesis that arsenic hyperaccumulation in this fern could function as a defense against insect herbivory was tested.• Fronds from control and arsenic-treated ferns were presented to nymphs of the grasshopper Schistocerca americana . Feeding damage was recorded by visual observation and quantification of the fresh weight of frond left uneaten and number of fecal pellets produced over a 2-d period. Grasshopper weight was determined before and after 5 d of feeding.• Grasshoppers consumed significantly greater amounts of the frond tissue, produced more fecal pellets and had increased body weight on control plants compared with grasshoppers fed arsenic-treated ferns. Very little or none of the arsenic-treated ferns were consumed indicating feeding deterrence. In a feeding deterrent experiment with lettuce, sodium arsenite at 1.0 m M deterred grasshoppers from feeding whereas 0.1 m M did not. In a choice experiment, grasshoppers preferred to feed on lettuce dipped in water compared with lettuce dipped in 1.0 m M sodium arsenite.• Our results show that arsenic hyperaccumulation in brake fern is an elemental defense against grasshopper herbivory.

Southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae), is the most serious insect pest of St. Augustinegrass Stenotaphrum secundatum (Walter) Kuntze, a common lawngrass grown in southeastern U.S. states. Host plant resistance to southern chinch bug has been identified in the polyploid St. Augustinegrass 'FX-10' and the diploid 'Captiva'. The objective of this research was to identify possible physical mechanism(s) explaining chinch bug resistance in these cultivars. We studied the distribution of chinch bug salivary sheaths in the preferred tissue for feeding (the axillary shoot) of the two resistant cultivars and two susceptible cultivars, paired for ploidy ('Floratam', polyploid, and Palmetto, diploid). We also investigated the potential role of axillary shoot lignification and anatomy in chinch bug resistance. Salivary sheaths were more abundant on the outermost leaf sheath of axillary shoots of resistant cultivars compared with susceptible cultivars. In contrast, fewer salivary sheaths reached the innermost meristematic tissue in the axillary shoots of resistant St. Augustinegrass cultivars than in the two susceptible cultivars. The polyploid cultivars FX-10 and Floratam had higher total lignin in axillary shoots compared with the diploid cultivars Captiva and Palmetto. However, total lignin content was not correlated with resistance to southern chinch bug. Light microscopic studies found no differences in epidermal layer thickness among resistant and susceptible St. Augustinegrass cultivars. However, transmission electron microscopic studies revealed that the cell walls of the sclerenchyma cells around the vascular bundle of southern chinch bug-resistant FX-10 and Captiva were significantly thicker than the cell walls in susceptible Floratam and Palmetto. Our research suggests that the thick-walled sclerenchyma cells around the vascular bundle play a role in southern chinch bug resistance in St. Augustinegrass, possibly by reducing stylet penetration to the vascular tissue.

The southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae), is the most important insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, in Florida and other Gulf Coast states. Resistance to southern chinch bug was identified previously in St. Augustinegrass lines 'FX-10' and NUF-76. Choice and no-choice tests and ovipositional and developmental studies were conducted to determine the categories of resistance in FX-10 and NUF-76 to southern chinch bug. When adult chinch bugs had a choice among attached stolons of three susceptible lines ('Floratam', 'Bitter Blue', and 'Palmetto') and the two resistant lines, chinch bugs were found significantly more often over a 5-d period on the susceptible lines. This result indicates the presence of antixenosis in the resistant lines FX-10 and NUF-76. In a no-choice study, chinch bugs produced less than half as many excretory spots on FX-10 as on the susceptible lines. Significantly fewer excretory spots produced by chinch bugs confined on NUF-76 accumulated by days 3 and 5 after release; however, on the first 2 d, the accumulative number of excretory spots was not significantly less than that found on susceptible lines. The no-choice study confirmed a high level of antixenosis in FX-10, a moderate level of antixenosis in NUF-76, and possible antibiosis in NUF-76. Ovipositional and developmental studies were conducted using only Floratam (a widely planted cultivar that was formerly resistant to B. insularis) and the two resistant lines. Adults released on Floratam produced 11 and 5 times more eggs and 18 and 9 times more offspring than adults on FX-10 and NUF-76, respectively. Plant anatomical and biochemical studies are required to investigate the exact cause of antixenosis in FX-10 and NUF-76 and possible antibiosis in NUF-76.

The attractiveness of sticky traps of eight colors for two parasitoids Amitus hesperidum Silvestri and Prospaltella opulenta Silvestri, and seven species of coccinellid predators of the citrus blackfly, Aleurocanthus woglumi Ashby (Homoptera: Aleyrodidae) was evaluated in insectory and field tests. Yellow traps captured significantly more parasitoids and coccinellids than other colors tested; captures were greatest in traps placed in the lower half of citrus trees. These traps can be used to survey for and monitor the population trends of the citrus blackfly and its natural enemies. Since the successful implementation of biological control of the citrus blackfly, Aleurocanthus woglumi, in Florida (Dowell et al., 1979a) and Texas (Ketner & Rosier, 1978), increased emphasis has been placed on acquiring information useful in approaches to the management of this pest. Survey techniques for A. woglumi have been developed in groves (Hart et al., 1978) and urban areas (Dowell & Cherry, 1980), and information obtained on the impact of several pesticides on predators and parasitoids of this pest (Fitzpatrick et al., 1978). Traps have been devised and used for monitoring changes in citrus blackfly numbers (Harlan et al., 1979, Hart et al., 1978, Dowell et al., 1979b, Meyerdirk et al., 1979, Fitzpatrick et al., 1979) but no equivalent system exists for estimating the abundance of predators or parasitoids of this pest. This information is needed in pest management programs to monitor population levels of the pest and its natural enemies, to time insecticide sprays for maximal pest control with minimal damage to beneficial insects and to aid in the survey for citrus blackfly and its parasitoids throughout the state. Here we present the results of tests with sticky traps to survey and monitor both parasitoids and predators of the citrus blackfly. RÉSUMÉ PIÈCES POUR ÉVALUER LES POPULATIONS DE PARASITOSES ET DE COCCINELLES PRÉDATRICES DE L'ALEURODE. ALEUROCANTHUS WOGLUMI Nous avons évalué l'attraction de Amitus hesperidum Silvestri et Prospaltella opulenta Silvestri, parasitoïdes d'Aleurocanthus woglumi Ashby et de 7 espèces de Coccinellides prédatrices de cette espèce, par des pièges à glu de 8 couleurs différentes (jaune, orange, rouge, bleu, vert, noir, blanc et transparent). Les pièges jaunes capturent significativement plus de parasitoïdes et de coccinelles que les autres couleurs; les captures sont plus importantes avec des pièges placés dans la moitié inférieure des citronniers. Ces pièges peuvent être utilisés pour suivre et contrôler l'évolution des populations d'A. woglumi et de ses parasitoïdes et coccinelles prédatrices.